This invention relates in general to vehicle axle assemblies and in particular to an improved method for forming a banjo-type housing for such an axle assembly.
Axle assemblies are well known structures which are in common use in most vehicles. Such axle assemblies include a number of components which are adapted to transmit rotational power from an engine of the vehicle to the wheels thereof. Typically, an axle assembly includes a differential which is rotatably supported within a non-rotating carrier. The differential is connected between an input drive shaft extending from the vehicle engine and a pair of output axle shafts extending to the vehicle wheels. The axle shafts are contained in respective non-rotating tubes which are secured to the carrier. Thus, rotation of the differential by the drive shaft causes corresponding rotation of the axle shafts. The carrier and the tubes form a housing for these drive train components of the axle assembly, inasmuch as the differential and the axle shafts are supported for rotation therein.
Axle housings are generally classified into two basic types. The first axle housing type is a unitized carrier construction, commonly referred to as a Salisbury or Spicer type axle assembly. In this structure, the carrier (which houses the rotatable differential) is directly connected to the two tubes (which house the rotatable axle shafts). An opening is provided at the rear of the carrier to permit assembly of the differential therein. This opening is closed by a cover during use. Unitized carrier axle housing constructions of this type are economical to manufacture and are readily adaptable for a variety of vehicles.
The second axle housing type is a separable carrier construction. In this structure, the axle tubes are connected together by a central member which is formed separate and apart from the carrier. This central member is generally hollow and cylindrical in shape, having a large generally circular opening formed therethrough. During assembly, the differential is first assembled within the carrier, then the carrier is secured to the central member. The overall shape of this type of axle housing (i.e., the generally round shape of the central member and the elongated tubes extending therefrom) generally resembles the shape of a banjo musical instrument. Hence, this type of axle housing is commonly referred to as a banjo type axle housing. Banjo type axle housings are advantageous because the carrier and differential can be removed from the axle assembly for service without disturbing the other components thereof.
In the past, several methods have been employed to form banjo type axle housings. A first known method involved forming the hollow cylindrical central member and the two tubes as three separate pieces. The tubes were then secured to the central member by welding or other means to form the housing. A second known method involved forming the entire housing from a single tubular blank. A hole was cut through the center of the blank, then formed into the hollow cylindrical central member, while the opposed end portions of the blank extended outwardly therefrom to form the tubes. A third known method involved forming the central member integrally from the ends of the two tubes. This was accomplished by splitting one end of each of the two tubes, spreading the two split ends apart, and securing the two spread ends together to form the hollow cylindrical central member.
Following the construction of the banjo type axle housing by any of these methods, flanges are formed or otherwise secured to the outer ends of the tubes. These flanges provide mounting surfaces for brakes and other components of the wheel ends to be mounted onto the axle assembly. Thus, it will be appreciated that the positions of the flanges relative to one another and relative to the other components of the axle assembly (such as the carrier, the differential, and the axle shafts) is important. Improper alignment of these components can cause vibration, noise, and premature wear.
While the above-described known methods have been used successfully to form banjo type axle housings, it has been found that all require numerous manufacturing steps to insure that the various components of the axle assembly are properly positioned relative to one another. Thus, it would be desirable to provide an improved method for forming a banjo type axle housing which does not require as many steps as are performed in known methods, thus reducing the time and cost of manufacture.